1. Field of the Invention
The present invention relates to buckles for a band and devices using such buckle to be worn on a user's body.
2. Description of the Related Art
Divers generally wear a wristwatch on his or her wrist depending on himself or herself or on the surrounding circumstances. The diver may or may not put on a wetsuit. Therefore, the diver's band buckle and the device to be worn on an a part of his or her body are required to have the following conditions:
(1) The length of the wristband is capable of being largely, easily, rapidly and appropriately adjusted depending on the diameter of a part of the driver's body on which the wristwatch or device is worn:
(2) The number of parts of the buckle and device protruding outward is small and the buckle and device are difficult to catch objects present therearound; and
(3) The buckle and device are not easily disengaged from the part of the diver's body, for example, due to shocks.
In order to meet these requirements, the applicants have proposed a band buckle for a diver as disclosed in Japanese Published Unexamined Patent Application 2001-292815. This buckle includes a slider connected pivotally at one end to one band, a bottom plate connected pivotally at one end to the other end of the slider so that the same is extendable therefrom, an intermediate plate pivoted at one end to the other end of the bottom plate so as to be foldable over the bottom plate, an upper cover pivoted at one end to the other end of the intermediate plate so as to be folded over the intermediate plate and pivoted at the other end to the other band, a safety cover turned over the upper cover of the folded buckle to prevent the turning of the upper cover, a latch mechanism which is operated by the opening of the safety cover, thereby allowing the slider fixed so far to the bottom plate to extend/retract freely, and a fixing mechanism which fixes the upper cover and the intermediate plate in a folded state on the intermediate plate.
The latch mechanism of this buckle comprises a pair of opposite latch pawls attached movable on a shaft and engaging a pair of parallel serrations, respectively, formed on the slider to stop its extension, a coil spring provided between the pair of latch pawls for forcing the respective latch pawls against the respective serrations, and a cam pivoted to the shaft so as not to move axially for pushing the respective latch pawls at their pressure reception ends to move the latch pawls inward against the resiliency of the coil spring. When the safety cover is turned and then opened so as to be upstanding, the cam is turned, thereby disengaging the pair of latch pawls from the pair of serrations.
The fixing mechanism comprises a T-shaped protrusion provided on the bottom plate, and a pair of hook-like buttons provided within a sleeve of the upper cover and biased by fixing springs so as to be extensible outward through both sides of the upper cover, thereby holding the T-shaped protrusion between ends thereof with lower inclined surfaces thereof. When the pair of hook-shaped buttons are compressed inward by fingers, the holding ends of the pair of hook-like buttons are opened, thereby releasing the T-shaped protrusion.
The diver's band buckle is very easy to handle because the length of the band is greatly changed by the slider and only turning and opening the safety cover is required to adjust the band length. A folded state of an articulated structure composed of the intermediate and bottom plates and the upper cover is doubly ensured by the fixing mechanism and the safety cover. Thus, the wristwatch worn by the band with the buckle on the user's wrist does not easily come off even by shocks. In addition, the buckle has few outward protruding parts such as catch peripheral objects undesirably. Thus, the buckle satisfies all the above-mentioned requirements.
However, the latch mechanism of this buckle is made of many parts including the cam, coil spring and pair of latch pawls, thereby making the structure complicated and expensive.